Endoscopes are used in various medical procedures as a less invasive alternative to more traditional surgical operations. Typically, an endoscope is inserted into the patient through either a natural orifice in the body such as the oral cavity, or through an incision made in the skin of the patient, so as to gain access to an internal part of the patient's anatomy. Once the endoscope is positioned within the patient, the physician can view the diseased or damaged area of the anatomy through a series of lenses or optic fibers within the endoscope. These lenses or optic fibers likewise provide illumination to the targeted anatomical area.
The endoscope may also employ one or more extra channels through which operating instruments may be passed. Such operating instruments may include dilation balloons, irrigation catheters, electrosurgical probes, papillotomes, cutting forceps or snares, or tissue sampling devices. These extra channels through the endoscope may also be used for the delivery of fluids or gasses, or to provide suction to the targeted anatomical area. Some endoscopes also include operating handles having controls for manipulating the tip of the endoscope so as to permit the endoscope to be maneuvered through the patient's anatomy.
In endoscopic procedures employing an operating instrument passed through the endoscope, it is often necessary to pass a wire guide through the catheter of the operating instrument. For example, in ERCP procedures, an endoscope is inserted into the patient's mouth and through the esophagus, stomach, and duodenum until it reaches the area where the ducts of the biliary tree and the pancreas open into the duodenum. This area is called the papilla of Vater. The physician then utilizes the endoscope's optics to view and diagnose any problems in the liver, gallbladder, bile ducts, and pancreas. The physician may also inject dyes (contrast) through the channel of the endoscope. The dyes are visible with x-rays, and aid the physician in the diagnosis.
In some patients, the diagnosis reveals the presence of calculi in the common duct, which are typically formed by secretions and mineral deposits. The calculi can cause an interruption of liver bile flow into the duodenum, and can irritate the surrounding tissue, thereby further interrupting the flow of bile. Any such obstructions in the papilla of Vater are typically removed or otherwise alleviated with a papillotome. The papillotome comprises an electrically conductive cutting wire extending through a multi-lumen catheter, which is inserted through the channel of the endoscope. One lumen is utilized for passing the electrically conductive wire therethrough, while another lumen is utilized for extending a wire guide therethrough. The wire guide is used to position the papillotome at the proper anatomical location. The proximal end of the papillotome typically includes a manually operated handle attached to the cutting wire that permits the distal end of the catheter to be deflected. This is done so as to form a loop at the distal end of the cutting catheter to engage tissue and, more particularly, to engage the papilla so as to enlarge the opening thereat.
Medical catheters for use with endoscopes are typically longer than the overall length of the endoscope. For example, endoscopes for use in medical procedures of the type described above typically have an overall length of 150–160 cm. Medical catheters for use with these endoscopes, such as the papillotome described above, typically have an overall length of approximately 200 cm. The catheter is longer than the endoscope so as to permit the distal end of the catheter to extend a sufficient distance beyond the distal end of the endoscope to perform cannulation or other procedures. However, the additional length of the catheter relative to the endoscope creates certain problems, particularly with respect to the insertion and manipulation of a wire guide through the catheter.
For example, when the catheter is used to perform a medical procedure such as sphincterotomy, the distal end of the catheter is only extended a short distance beyond the distal end of the endoscope. In other words, only that portion of the distal end of the catheter that comprises the operational device, such as a cutting wire, is typically extended beyond the end of the endoscope. A substantial portion of the catheter that is adjacent to the catheter's handle therefore extends from the proximal end of the endoscope. As a consequence, the catheter's handle and the wire guide port, which is typically located near the catheter's handle, are spaced a substantial distance away from the endoscope. This spaced arrangement, however, makes it difficult for the physician to simultaneously insert or manipulate a wire guide inserted into the catheter and manipulate the endoscope. A physician will therefore usually elect to personally manipulate the endoscope, and rely on an assistant to manipulate the wire guide. This can be problematic because of the difficulty in issuing and/or following voice commands between the physician and the assistant in an accurate and timely manner.
Accordingly, there is a need for a wire guided medical catheter that permits the physician to simultaneously manipulate a wire guide inserted through the catheter and an endoscope.
Another problem with conventional medical catheters of the type described above is that it is often difficult to accurately determine how far the distal end of the catheter extends beyond the distal end of the endoscope. For example, it may be desirable to extend the distal end of the catheter a fixed distance beyond the end of the endoscope so as to enable an operational tool on the distal end of the catheter to perform a specific medical procedure. This is ordinarily accomplished by observing the length of the proximal end of the catheter extending from the proximal end of the endoscope, and then estimating the length of the distal end of the catheter extending beyond the distal end of the endoscope. However, because conventional medical catheters are substantially longer than the endoscopes in which they are typically used, such visual estimates are difficult to make with any accuracy.
Accordingly, there is a need for a wire guided medical catheter that enables the physician to quickly and accurately determine the length of the distal end of the catheter extending beyond the distal end of the endoscope.